A piezoelectric resonator device typified by a piezoelectric resonator is widely used in a mobile communication device such as a mobile phone. One of piezoelectric resonator plates used for the piezoelectric resonator is a crystal resonator plate. The crystal resonator plate includes excitation electrodes on front and back principal surfaces, extraction electrodes for extracting these excitation electrodes to end portions of the crystal resonator plate, and similar member. In this crystal resonator plate, a terminal electrode is formed inside of a box-shaped package with an open top, and a bonding portion (a connecting electrode) is formed in an end portion of the extraction electrode of the crystal resonator plate. The terminal electrode and the bonding portion are bonded together via a conductive bonding material. The opening portion is hermetically enclosed by a lid so as to constitute a surface-mount crystal resonator.
For example, in the crystal resonator disclosed in Patent Literature 1, a crystal resonator plate and the package are electrically and mechanically bonded together via the conductive bonding material such as a metal bump. To improve mutual bonding strength, the excitation electrode and the connecting electrode that are formed in the crystal resonator plate are different in material of a base electrode and a method for forming electrodes.